On 11/22/2019 11:15 PM, Philip Thrift wrote:
On Friday, November 22, 2019 at 11:59:41 PM UTC-6, Brent wrote:
On 11/22/2019 9:35 PM, Bruce Kellett wrote:
On Sat, Nov 23, 2019 at 7:02 AM 'Brent Meeker' via Everything
List <[email protected] <javascript:>> wrote:
On 11/22/2019 6:14 AM, John Clark wrote:
Why does the act of measurement seem to override the
evolution of Schrödinger's wave function, and what exactly
does a "measurement" even mean? Many Worlds is the only
interpretation that can give a credible answer to that question
The epistemological interpretation also gives a credible answer.
Have you ever seen the paper by Pusey, Barrett, and Rudolph
(arXiv:1111.3328)? They prove a theorem that places limitations
on the viability of a purely epistemic interpretation of the wave
function: "Here we show that any model in which a quantum state
represents mere information about an underlying physical state of
the system, and in which systems prepared independently have
independent physical states, must make predictions which
contradict those of quantum theory."
Which continues:
"The argument depends on few assumptions. One is that a
system has a “real physical state” – not necessarily com-
pletely described by quantum theory, but objective and
independent of the observer. This assumption only needs
to hold for systems that are isolated, and not entangled
with other systems. Nonetheless, this assumption, or
some part of it, would be denied by instrumentalist ap-
proaches to quantum theory, wherein the quantum state
is merely a calculational tool for making predictions con-
cerning macroscopic measurement outcomes."
There is also this paper, which discusses some loopholes the the
assumptions of the PBR theorem:
Implications of the Pusey-Barrett-Rudolph quantum no-go theorem
Maximilian Schlosshauer, Arthur Fine
(Submitted on 21 Mar 2012 (v1), last revised 27 Jun 2012 (this
version, v3))
Pusey, Barrett, and Rudolph introduce a new no-go theorem for
hidden-variables models of quantum theory. We make precise the
class of models targeted and construct equivalent models that
evade the theorem. The theorem requires assumptions for models of
composite systems, which we examine, determining "compactness" as
the weakest assumption needed. On that basis, we demonstrate
results of the Bell-Kochen-Specker theorem. Given compactness and
the relevant class of models, the theorem can be seen as showing
that some measurements on composite systems must have built-in
inefficiencies, complicating its testing.
Comments: 4 pages. v2: tweaked presentation, new title; v3:
minuscule edits to match published version
Subjects: Quantum Physics (quant-ph)
Journal reference: Phys. Rev. Lett. 108, 260404 (2012)
DOI: 10.1103/PhysRevLett.108.260404
Cite as: arXiv:1203.4779 [quant-ph]
(or arXiv:1203.4779v3 [quant-ph] for this version)
Brent
*Epistemic interpretations of quantum theory have a measurement problem*
Quantum Physics and Logic 2019 - https://qpl2019.org/
https://qpl2019.org/wp-content/uploads/2019/05/QPL_2019_paper_2.pdf
/We have demonstrated that state update under measurement poses a
serious challenge to ψ-epistemic interpretations of quantum theory in
the ontological models framework: all currently known ψ-epistemic
models for full quantum theory in d ≥ 3 cannot faithfully represent/
/state update. This runs in direct contrast to the prevailing view
that ψ-epistemic models provide a compelling explanation of state update./
/Within the ontological models formalism, epistemic//
//models can be given a precise mathematical definition//
//called the ψ-epistemic criterion [22]. This precise criterion //
//allows the possibility of conclusively ruling out this//
//type of model. Outside of this framework, it is unlikely//
//that ψ-epistemic models can be precluded with any kind//
//of certainty; doxastic interpretations, for example, do not//
//fit neatly into the ontological models framework and thus//
//are not necessarily ruled out by these no-go theorems.
/Which is why QBism interprets the formalism as being about the beliefs
of the person using it.
Brent/
/
@philipthrift.
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